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Staging

Staging is the process of finding out how much cancer there is in a person’s body and where it’s located. It’s how the doctor learns the stage of a person’s cancer.

Doctors use staging information to plan treatment and to help predict a person’s outlook (prognosis). Cancers with the same stage tend to have similar outlooks and are often treated the same way. The cancer stage is also a way for doctors to describe the extent of the cancer when they talk with each other about a person’s cancer.

Why is staging needed?

Doctors need to know the amount of cancer and where it is in the body to be able to choose the best possible treatment. For example, the treatment for early stage breast cancer may be surgery and radiation, while a more advanced stage of breast cancer may need to be treated with chemotherapy, too. Doctors also use the stage to help predict the course a cancer will likely take.

In a larger sense, doctors use staging information when they compare cancer treatments. It allows researchers to make sure study groups are actually similar when they test cancer treatments against one another, measure outcomes, and more.

What is the doctor looking for when staging cancer?

Doctors look for the primary cancer (the original tumor) and also check for other tumors. They will look at the size, number, and location of any tumors, to see if the cancer has spread far away.

Doctors also look at nearby lymph nodes, to find out if cancer has spread into them. Lymph nodes are small bean-shaped collections of immune system tissue found along lymphatic vessels. They remove cell waste, germs, and other harmful substances from lymph. They help fight infections and also have a role in fighting cancer, but cancers can spread through them.

In some kinds of cancer, cancer cell type and grade (as seen under a microscope) become part of the stage.

More details on staging are given in the “Staging systems” section below.

How are cancers staged?

Doctors gather different types of information about a cancer to figure out its stage. Depending on where the cancer is located, the physical exam may give some clue as to how much cancer there is. Imaging tests like x-rays, CT scans, MRIs, ultrasound, and PET scans may also give information about how much and where cancer is in the body.

Often, biopsy is needed to confirm the diagnosis of cancer. Biopsies are also needed to find out if an abnormal spot on an imaging test is really cancer spread. A biopsy involves taking out tumors or pieces of tumors and looking at them under the microscope. Some biopsies may be done during surgery. But many types of biopsies are done by removing small pieces of tumor through a thin needle or through a flexible lighted tube called an endoscope. The different kinds of biopsies used to check for cancer are described in our Surgery document.

Types of staging

All staging is done at the time of diagnosis, before any treatment is given. There are 2 major types of staging.

Clinical staging

This is an estimate of how much cancer there is based on the physical exam, imaging tests (x-rays, CT scans, etc.), and tumor biopsies. For some cancers, the results of other tests, such as blood tests, are also used in staging. The clinical stage is a key part of deciding the best treatment to use. It’s also the baseline used for comparison when looking at the cancer’s response to treatment.

Pathologic staging

Pathological staging (also called surgical staging) relies on what is learned about the cancer during surgery. Often this is surgery to remove the cancer and nearby lymph nodes, but sometimes surgery may be done to just look at how much cancer is in the body and take out tissue samples.

In some cases, the pathologic stage may be different from the clinical stage (for instance, if the surgery shows the cancer has spread more than it was thought to have spread before surgery). The pathological stage gives the health care team more precise information that can be used to predict treatment response and outcomes (prognosis).

Staging systems

At one time there were many different systems used to stage cancers, and sometimes different systems were used to stage the same type of cancer. But many of these systems did not give doctors very useful information. There are still different types of staging systems, but the most common and useful staging system used around the world today is the TNM system.

The TNM system

The American Joint Committee on Cancer (AJCC) and the International Union for Cancer Control (UICC) maintain the TNM classification system as a tool for doctors to stage different types of cancer based on certain standards. It’s reviewed every 6 to 8 years to include advances in our understanding of cancer.

In the TNM system, each cancer is assigned a letter or number to describe the tumor, node, and metastases.

  • T stands for tumor. It’s based on the size of the original (primary) tumor and whether it has grown into nearby tissues
  • N stands for node. It tells whether the cancer has spread to the nearby lymph nodes
  • M stands for metastasis. It tells whether the cancer has spread to distant parts of the body

The T category describes the original (primary) tumor. The tumor size is usually measured in centimeters or cm (2½ cm = about 1 inch) or millimeters or mm (10 mm = 1 cm).

  • TX means the tumor can’t be measured.
  • T0 means there is no evidence of primary tumor (it cannot be found).
  • Tis means that the cancer cells are only growing in the most superficial layer of tissue, without growing into deeper tissues. This may also be called in situ cancer or pre-cancer.
  • Numbers after the T – T1, T2, T3, and T4 – describe the tumor size and/or amount of spread into nearby structures. The higher the T number, the larger the tumor and/or the more it has grown into nearby tissues.

The N category describes whether the cancer has spread into nearby lymph nodes.

  • NX means the nearby lymph nodes cannot be evaluated.
  • N0 means nearby lymph nodes do not contain cancer.
  • Numbers after the N – N1, N2, and N3 – describe the size, location, and/or the number of lymph nodes involved. The higher the N number, the more lymph nodes there are that contain cancer.

The M category tells whether there are distant metastases (spread of cancer to other parts of body).

  • MX means metastasis can’t be evaluated.
  • M0 means that no distant cancer spread was found.
  • M1 means that the cancer has spread to distant organs or tissues (distant metastases were found).

Each cancer type has its own version of this classification system, so letters and numbers don’t always mean the same thing for every kind of cancer. For example, in some types of cancer T1 means the tumor is smaller than a centimeter, but in another type a T1 may be up to 2 centimeters. In still another cancer type, T may tell how far the cancer has invaded into the layers of tissue.

Some cancer types also have special groupings that are different from other cancer types. For instance, for some cancers, classifications may have subcategories, such as T3a and T3b, while others may not have an N3 category.

Stage grouping

Once the values for T, N, and M have been determined, they are combined, and an overall stage is assigned. For most cancers, the stage is a Roman numeral from I to IV, where stage IV (4) is the highest and means more cancer is present than in the lower stages. Sometimes stages are subdivided as well, using letters such as A and B.

For instance, a T1, N0, M0 breast cancer would mean that the primary breast tumor is less than 2 cm across (T1), does not have lymph node involvement (N0), and has not spread to distant parts of the body (M0). This would make it a stage I cancer. A T3, N1, M1 breast cancer, on the other hand, would be a stage IV cancer. In this case the tumor would be more than 50mm (2 inches) across (T3), it would have spread to nearby lymph nodes (N1), and the cancer would have also been found in another part of the body (M1).

Stage 0 is carcinoma in situ for most cancers. This means the cancer is at a very early stage, is only in the area where it first developed, and has not spread. Not all cancers have a stage 0.

Stage I cancers are the next least advanced and often have a good prognosis (outlook for survival). As the stage number goes up the cancers are more advanced (bigger and more widespread). The outlook is usually not as good as it is for the lower stages, but most of these cancers can still be treated.

Other factors that can affect the stage

For some cancers, the values for T, N, and M aren’t the only things that determine the stage. Some other factors that may be taken into account include:

Grade: For most cancers, the grade is a measure of how abnormal the cancer cells look under the microscope. This is called differentiation. Grade is important because cancers with more abnormal-looking cells tend to grow and spread faster.

The grade is usually assigned a number from 1 to 3 or 4. The lower the number, the more the cancer cells look like cells from normal tissue. Higher-grade cancers (meaning that the cancer cells look very different from normal cells) often have a worse prognosis, and may need different treatments than low-grade cancers. Even when the grade doesn’t change a cancer’s stage, it may still affect the outlook and/or treatment.

For some types of cancer, a different grading system is used. For prostate cancer, something called a Gleason score is used to sum up the grade. First, a grade (a number from 1 to 5) is assigned to the 2 areas that make up most of the cancer. These numbers are added together to get the Gleason score, which can be a number from 2 to 10.

For some sarcomas, the grade is not only based on differentiation. It also takes into account how many of the cells appear to be dividing, and how much of the tumor is made up of dying tissue. This gives doctors an idea of how fast the cancer is growing and how quickly it is likely to spread.

Cell type: Some types of cancer can be made up of different types of cells. Because the type of cancer cell can affect treatment and outlook, it may be a factor in staging. Cancer of the esophagus, for example, comes in 2 main cell types: squamous cell and adenocarcinoma. Cancers that are squamous cell are staged differently than those that are adenocarcinoma.

Tumor location: For some cancers, where the tumor is located affects outlook and is taken into account in staging. For cancer of the esophagus, for example, staging factors in whether the cancer is in the upper, middle, or lower third of the esophagus.

Tumor marker levels: For prostate cancer, the level of the tumor marker prostate specific antigen (PSA) is taken into account in assigning stage.

Other staging systems

Not all cancers are staged using the TNM system. Some cancers grow and spread in a different way—there might not even be a tumor. For example, leukemias (cancers of the blood) affect the blood and bone marrow throughout the body, and so they are not staged the same as solid tumor cancers. Cancers in or around the brain are also not staged using the TNM system, since these cancers tend to spread to other parts of the brain and not to lymph nodes or other parts of the body. Staging systems other than the TNM system are often used for Hodgkin disease and other lymphomas, too, as well as for some childhood cancers.

The International Federation of Gynecologists and Obstetricians (FIGO) has a staging system for cancers of the female reproductive organs. The TNM stages closely match the FIGO stages, which makes it fairly easy to convert stages between these 2 systems.

Other, older staging systems (such as the Dukes system for colorectal cancer) may still be used by some doctors. If your doctor uses another staging system, you may want to find out if the stage can be translated into the TNM system. This will often help if you want to read more about your cancer and its treatment, since TNM is more widely used.

A cancer’s stage does not change

An important point some people have trouble understanding is that the stage of a cancer does not change over time, even if the cancer progresses. A cancer that comes back or spreads is still referred to by the stage it was given when it was first found and diagnosed—information about the current extent of the cancer is added to it.

For example, let’s say a woman was first diagnosed with stage II breast cancer and the cancer went away with treatment. But then it came back with spread to the bones. The cancer is still called a stage II breast cancer, now with recurrent disease in the bones. If the breast cancer did not respond to treatment and spread to the bones it’s called a stage II breast cancer with bone metastasis. In either case, the original stage does not change and it’s not called a stage IV breast cancer. A stage IV breast cancer refers to a cancer that has already spread to a distant part of the body when it’s first diagnosed. A person keeps the same diagnosis stage, but more information is added to the diagnosis to explain the current state of the disease.

This is important to understand because survival statistics and information on treatment by stage for specific cancer types refer to the stage when the cancer was first diagnosed. The survival statistics related to stage II breast cancer that has recurred in the bones may not be the same as the survival statistics for stage IV breast cancer.

At some point you may hear the term “restaging.” Restaging is the term sometimes used for doing tests to find the extent of the cancer after treatment. This is rarely done, but it may be used to measure the cancer’s response to treatment or to assess cancer that has come back (recurred) and will need more treatment. Often this involves the same tests that were done when the cancer was first diagnosed: physical exams, imaging tests, biopsies, and maybe surgery. After these tests a new stage may be assigned. It’s written with a lower-case “r” before the new stage to note that it’s different from the stage at diagnosis. The original stage at diagnosis always stays the same. While testing to see the extent of cancer is common during and after treatment, actually assigning a new stage is rarely done, except in clinical trials.

Finding out more about your type of cancer

If you are looking for details on staging or grading for a certain type of cancer, you can find this information in each of our documents on specific cancer types. You can get any of these cancer site documents on our Web site or by calling our toll-free number below.

To learn more

More information from your American Cancer Society

The following related information may also be helpful to you. These materials may be ordered from our toll-free number, 1-800-227-2345, or read online at www.cancer.org.

Dealing with cancer

Coping With Cancer in Everyday Life (also in Spanish)

After Diagnosis: A Guide for Patients and Families (also in Spanish)

Talking With Your Doctor (also in Spanish)

Cancer tests and treatments

Imaging (Radiology) Tests

Testing Biopsy and Cytology Specimens for Cancer

Surgery (also in Spanish)

Understanding Chemotherapy (also in Spanish)

Understanding Radiation Therapy (also in Spanish)

National organizations and Web sites*

Along with the American Cancer Society, other sources of information and support include:

National Cancer Institute
Toll-free number: 1-800-4-CANCER (1-800-422-6237)
Web site: www.cancer.gov

    For free, accurate, up-to-date cancer information for patients, their families, and the general public

American Joint Committee on Cancer (AJCC)
Telephone: 312-202-5313
Web site: www.cancerstaging.org

    Offers “Cancer Staging - What You Need to Know” (www.cancerstaging.org/staging/needtoknow.pdf), a brochure for patients and families that explains the TNM system, lists some commonly staged cancers, defines the concept of stage grouping, and discusses the purpose of the cancer registry

*Inclusion on this list does not imply endorsement by the American Cancer Society.

No matter who you are, we can help. Contact us anytime, day or night, for cancer-related information and support. Call us at 1-800-227-2345 or visit www.cancer.org.

References

Edge SB, Byrd DR, Compton CC, Fritz AG, Greene FL, Trotti A, eds. American Joint Committee on Cancer Staging Manual. 7th ed. New York, NY: Springer; 2010.

Yarbro CH, Frogge MH, Goodman M, Groenwald SL, eds. Cancer Nursing Principles and Practice. 5th ed. Sudbury, MA: Jones and Bartlett Publishers, Inc. 2000.

Last Medical Review: 06/07/2012
Last Revised: 06/07/2012